Background: The intraventricular delay is a determinant of functional mitral regurgitation (MR). MR contributes to the progression of congestive heart failure (CHF) and represents a marker of a worse outcome. The aim of this study was to test the hypothesis that cardiac resynchronization therapy (CRT) significantly reduces MR in CHF patients with ventricular conduction defects.
Methods: We studied 45 consecutive patients (37 males, 8 females, mean age 72 +/- 9 years) in NYHA class III-IV, with left ventricular ejection fraction < 35%, QRS duration > 150 ms with left bundle branch block or already paced in the right ventricle, and MR score > or = 1. We compared the QRS duration and the basal peak of the V-wave before and 15 min after CRT. Before implantation and 1 week after we measured ejection fraction, systolic mitral annulus diameter, MR area, left atrial area, MR area expressed as the percentage of the left atrial area (%MR area), and MR score (range 1-4).
Results: The QRS duration before and after CRT was 195 +/- 30 and 156 +/- 17 ms (p < 0.01) respectively. Significant decreases were observed in the systolic mitral annulus diameter (-7.9%, p < 0.001), MR area (-38%, p < 0.001), MR score (-33.4%, p < 0.001), left atrial area (-5.9%, p < 0.05), and %MR area (-36.2%, p < 0.001). The peak of the V-wave decreased by 33%. The ejection fraction increased by 46% (p < 0.001).
Conclusions: CRT significantly reduces MR and improves cardiac function in patients with CHF and ventricular conduction defects. The combination of the degree of MR and a low ejection fraction and large QRS duration may contribute to a more reliable patient selection for CRT.